The particle nature of dark matter remains one of the most significant open questions in high energy physics. The lack of a definitive signal in traditional searches for WIMP-like dark matter has motivated an increased focus on so-called dark sector scenarios, in which the Standard Model (SM) is extended with new particles that are neutral under the SM gauge group but charged under new "dark forces", interacting with the SM only through an additional mediator particle. A particularly compelling class of these models is dark QCD, where the dark sector contains its own confining gauge group, analogous to SM QCD, giving rise to a spectrum of composite dark states. These models can produce striking collider signatures, including displaced vertices, jets containing invisible constituents, and emerging jets, whose charged particle content gradually emerges as the dark states decay back to the SM. These signatures pose significant challenges for standard reconstruction techniques, requiring the development of novel identification strategies. In this talk, I will present recent ATLAS efforts to probe dark QCD signatures, including searches for exotic decays of the Higgs boson to long-lived particles, the first ATLAS search for emerging jets, and the reconstruction techniques that enable the identification of these topologies. Together, these results illustrate how ATLAS is expanding its reach into dark sector parameter space and opening new avenues in the search for dark matter.